One, completing a round trip, and the other, it's off on a one-way ticket.

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In some cases, the two-ticket trip puts you on the same airplanes that you would have booked with a one-ticket itinerary.

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Look for somebody who's bought a one-way ticket, or look for somebody who's bought a round trip ticket.

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Umar Farouk AbdulMutallab, the man accused of trying to blow up a U.S. airliner bound for Detroit, Michigan, had a one-way ticket from Accra, Ghana, to Lagos, Nigeria, and a round-trip ticket for his trip from Lagos to the Netherlands and then to Detroit, according to the Nigerian Aviation Authority.

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